Modelling respiratory infection control measure effects

One of the most pressing issues in facing emerging and re-emerging respiratory infections is how to bring them under control with current public health measures. Approaches such as the Wells-Riley equation, competing-risks model, and Von Foerster equation are used to prioritize control-measure efforts. Here we formulate how to integrate those three different types of functional relationship to construct easy-to-use and easy-to-interpret critical-control lines that help determine optimally the intervention strategies for containing airborne infections. We show that a combination of assigned effective public health interventions and enhanced engineering control measures would have a high probability for containing airborne infection. We suggest that integrated analysis to enhance modelling the impact of potential control measures against airborne infections presents an opportunity to assess risks and benefits. We demonstrate the approach with examples of optimal control measures to prioritize respiratory infections of severe acute respiratory syndrome (SARS), influenza, measles, and chickenpox.

Reliability of self-reported willingness-to-pay and annual income in patients treated for toenail onychomycosis

BACKGROUND

Willingness-to-pay (WTP) is a health economics measure that has recently been used for skin diseases to evaluate patients' quality of life. However, the reliability of this measure has not been investigated in the dermatology literature and is essential in validating its use in health services research.

OBJECTIVES

This study evaluated the test-retest reliability of self-reported annual income and WTP, a health economics measure of disease impact, in patients with toenail onychomycosis.

METHODS

Forty-six patients enrolled in a randomized clinical trial comparing two different dosing regimens of terbinafine completed a self-administered questionnaire at baseline and 1 month later. The questionnaire asked: (i) how much patients would be willing to pay for a theoretical treatment with a cure rate of 85% for their current onychomycosis (10 categories: $0-50, $51-100, to > $800); and (ii) annual income (10 categories: $0-10,000 to > $200,000).

RESULTS

Forty-four patients reported WTP at both visits, and 55% reported the same WTP. The quadratic-weighted (Fleiss-Cohen) kappa statistic indicated moderate agreement (kappa = 0.50, 95% confidence interval, CI 0.24-0.75, P < 0.01) as did the Spearman rank-order correlation coefficient (r(s) = 0.57, P < 0.01; median difference = 0, P = 0.50). Strong agreement was shown among the 42 patients who reported income at both visits; 71% reported the same annual income category (kappa = 0.72, 95% CI 0.47-0.96, P < 0.01; r(s) = 0.68, P < 0.01; median difference = 0, P = 0.77). Age, disease severity and duration, previous therapy, self-reported annual income, and medication side-effects were not statistically associated with the reliability of WTP.

CONCLUSIONS

WTP and annual income demonstrated moderate and strong test-retest reliability, respectively. Self-reported WTP can serve as a reliable measure for future health economics research on onychomycosis.

A quantitative analysis of head movement behaviour during visual acuity assessment under prosthetic vision simulation

In most current vision prosthesis designs, head movement is the sole director of visual gaze and scanning due to the head-mounted nature of the camera. Study of this unnatural behaviour may provide insight into improved prosthesis designs and rehabilitation procedures. In this paper, we conducted a psychophysical study to investigate the characteristics of head movements of normally sighted subjects undergoing a visual acuity task in simulated prosthetic vision (SPV). In 12 naïve, untrained subjects, we recorded spontaneous changes in the amount of head movements during SPV sessions compared to control (normal vision) sessions. The observed behaviour continued to be refined until five or six sessions of practice. Increased head movement velocity was shown to be correlated to improved visual acuity performance, up to 0.3 logMAR, an equivalent of detecting details at half the physical size compared to complete deprivation of head movements. We postulate that visual scanning can as much as double the spatial frequency information in prosthetic vision. Increased head movement velocity observed when subjects were attempting smaller test items and for low-pass filtering schemes with higher cut-off frequencies may be further evidence that higher frequency content may be available through visual scanning, unconsciously driving subjects to increase head movement velocity.

A multi-functional online measurement system for neuron-microelectrode interface study

The goal of this paper is to develop a multifunctional measurement system for neuron-microelectrode interface study by LabVIEW. The system uses a commercial 60-channel microelectrode array (MEA) as an interface platform. These online functions of neuronal stimulation, extracellular potential recording, impedance monitoring, and data storage have been integrated into this system. Two offline analysis functions of wavelet de-noising and artifact removing are also included. The former two online functions are executed respectively by a NI-DAQ card and by a self-made analog frond-end amplifier, and Agilent 4284A LCR meter makes the impedance measurement. We have completed the basic functional verifications on a cultured MEA with PC-12.

Effect on prosthetic vision visual acuity by filtering schemes, filter cut-off frequency and phosphene matrix: a virtual reality simulation

Visual acuity of prosthetic vision was examined under virtual reality simulation. Prosthetic vision was simulated by first filtering an image using circular mean filters or Gaussian smoothing filters of different cut-off frequencies. Pixel values at 100 fixed sites of the filtered image were taken, sampling either with a regular rectangular or hexagonal matrix. Each pixel value was transformed into a Gaussian intensity profile centered at the corresponding position at which the sample was taken to simulate the evoked visual effect of an electric stimulation. Visual acuity scores of three subjects, each completing two sets of results, were recorded across different filtering schemes, cut-off frequencies and sampling matrices. The best mean score recorded was 1.55 logMAR, with the worst being 1.70 logMAR. The difference was mostly attributed to filter cut-off frequency. Differences between filtering schemes were insignificant. Results also showed emerging trends demonstrating differences between rectangular and hexagonal sampling matrices.

Location of putative stem cells in human periodontal ligament

BACKGROUND AND OBJECTIVE

The origin of cells in the mature periodontium, and the location of their progenitors, are still unknown. It is also unknown whether inflammation influences the number and distribution of these cells within the periodontium. Molecules such as STRO-1, CD146 and CD44 have been identified on a variety of mesenchymal stem cells. The aim of this study was to identify and localize putative stem cells in diseased and healthy human periodontal ligament using cell-surface markers for mesenchymal stem cells.

MATERIAL AND METHODS

Healthy and periodontitis-affected teeth were collected, fixed in 10% neutral-buffered formalin, decalcified and embedded in paraffin in preparation for immunohistochemistry. Antibodies against STRO-1, CD146 and CD44 were used to identify putative stem cells in the periodontal ligament.

RESULTS

Putative stem cells were identified in both healthy and diseased periodontal ligament. They were mainly located in the paravascular region and small clusters of cells were also found in the extravascular region. Wider distributions of these cells were detected in sections of diseased ligament.

CONCLUSION

Within the periodontal ligament of both healthy and diseased teeth, cells have been identified consistent with their identification as putative stem cells. The presence of an inflammatory reaction associated with periodontitis may enhance the number of these cells.

Application of immobilized cells to the treatment of cyanide wastewater

Cyanide is highly toxic to living organisms, particularly in inactivating the respiration system by tightly binding to terminal oxidase. To protect the environment and water bodies, wastewater containing cyanide must be treated before discharging into the environment. Biological treatment is a cost-effective and environmentally acceptable method for cyanide removal compared with the other techniques currently in use. Klebsiella oxytoca (K. oxytoca), isolated from cyanide-containing industrial wastewater, has been shown to be able to biodegrade cyanide to non-toxic end products. The technology of immobilized cells can be applied in biological treatment to enhance the efficiency and effectiveness of biodegradation. In this study, potassium cyanide (KCN) was used as the target compound and both alginate (AL) and cellulose triacetate (CTA) techniques were applied for the preparation of immobilized cells. Results from this study show that KCN can be utilized as the sole nitrogen source by K. oxytoca. The free suspension systems reveal that the cell viability was highly affected by initial KCN concentration, pH, and temperature. Results show that immobilized cell systems could tolerate a higher level of KCN concentration and wider ranges of pH and temperature, especially in the system with CTA gel beads. Results show that a longer incubation period was required for KCN degradation using immobilized cells compared to the free suspended systems. This might be due to internal mass transfer limitations. Results also indicate that immobilized systems can support a higher biomass concentration. Complete KCN degradation was observed after the operation of four consecutive degradation experiments with the same batch of immobilized cells. This suggests that the activity of the immobilized cells can be maintained and KCN can be used as the nitrogen source throughout KCN degradation experiments. Results reveal that the application of immobilized cells of K. oxytoca is advantageous to the maintenance of KCN degradation efficiency. Thus, it is conceivable that the immobilized cells of K. oxytoca would be applicable to the treatment of cyanide-containing wastewaters.

Cloning and nucleotide sequencing of the second internal transcribed spacer of ribosomal DNA for three species of Eimeria from chickens in Taiwan

Coccidiosis of chickens caused by protozoan parasites of the genus Eimeria (Coccidia: Eimeriidae) is an enteric disease that results in great economic losses throughout the world, including Taiwan. Using polymerase chain reaction (PCR) with primers specific for the second internal transcribed spacer (ITS-2) of ribosomal DNA (rDNA), three species of Eimeria, E. tenella, E. maxima, and E. acervulina have been successfully characterised from chickens in Taiwan. The sizes of PCR products from various isolates representing these three species were between 370 and 580 base pairs (bp). After cloning and sequencing of the PCR products, high nucleotide sequence identity (96.8-100%) was observed within a species. In addition, ITS-2 nucleotide sequences for E. tenella had higher homology (98.5-99.3%) than E. maxima (81.6-96.5%) when compared with appropriate sequences deposited in GenBank. To our knowledge, this is the first report of a 412-bp ITS-2 sequence for E. acervulina from chickens.

Multidetector computed tomography assessment on tumor size and nodal status in patients with locally advanced breast cancer before and after neoadjuvant chemotherapy

AIMS

To evaluate the utility of multidetector computed tomography (MCT) in assessing tumor size and nodal status in patients with advanced breast cancers before and after the neoadjuvant chemotherapy.

METHODS

Twenty-eight proven locally advanced breast cancer patients with 30 tumors were enrolled in this study. MCT was used to assess tumor size and axillary lymph nodes before and after the neoadjuvant chemotherapy. The correlation between tumor size on MCT and gross tumor size was tested.

RESULTS

The MCT measurements documented complete response in 3, partial response in 18, non-response in 8 and progressed in 1. The mean tumor diameters on pathology and post-chemotherapy MCT were 3.6cm (S.D.=+/-2.9cm) and 3.1cm (S.D.=+/-2.6cm), respectively. The Pearson correlation coefficient was 0.76 (p<0.001). The sensitivity, specificity, positive predictive valve, negative predictive valve and accuracy of MCT in diagnosing the axillary lymph node metastases after pre-operative neoadjuvant chemotherapy were counted, respectively, to 72%, 40%, 85.7%, 22.2% and 66.7%. All the 5 downstaged axillary nodal statuses from node-positive to node-negative on MCT had micrometastases.

CONCLUSION

MCT can be used to evaluate tumor size and nodal status in patients with advanced breast cancer. As there is a baseline MCT before chemotherapy for comparison, we are potentially aware of the possibility of false negative nodal micrometastases on the post-chemotherapy MCT.

Direct patterning of three-dimensional periodic nanostructures by surface-plasmon-assisted nanolithography

The technical applications of three-dimensional (3D) nanostructures demand a fabrication technique that is convenient and yet offers design flexibility. We describe here a nanofabrication technique called surface-plasmon-assisted three-dimensional nanolithography (3D-SPAN). By utilizing optical near-field interference patterns generated by surface plasmons (SPs), we have fabricated different 2D/3D periodic polymeric nanostructures in a typical photolithography setup. We have also shown here that the nanostructures fabricated by 3D-SPAN can be controlled easily in terms of size, layout, and defects by designing the SPAN mask. Because of its design flexibility and fabrication convenience, 3D-SPAN could be used to develop "photonics on a chip", where signal processing is carried out by photons instead of electrons and be extended to other applications of direct-writing 3D functional nanostructures.

Role of pleural fluid C-reactive protein concentration in discriminating uncomplicated parapneumonic pleural effusions from complicated parapneumonic effusion and empyema

The aim of this study was to determine whether pleural fluid C-reactive protein (CRP) is useful in distinguishing complicated parapneumonic pleural effusion (CPPE) and empyema from uncomplicated parapneumonic pleural effusions (UPPE). A total of 69 consecutive patients with parapneumonic effusions were enrolled in the study: 29 with UPPE, 29 with CPPE, and 11 with empyema. Concentrations of standard biochemical parameters together with CRP in the pleural fluid were measured using an immunoturbidimetric assay. Pleural CRP was significantly higher in CPPE (11.6 mg/dl) and in empyema (12.2 mg/dl) than in UPPE (3.9 mg/dl). A cutoff value of 8.7 mg/dl for pleural CRP in the diagnosis of CPPE and empyema resulted in a sensitivity, specificity, and area under the receiver-operating characteristic curve (AUC) of 0.80, 0.97 and 0.94, respectively. Traditional lactic dehydrogenase (LDH) > or = 1000 U/L and glucose < or = 60 mg/dl can differentiate CPPE and empyema from UPPE, with the sensitivity, specificity, and AUC achieving 0.75/0.60.1.00/1.00,0.95/0.22, respectively. However, for the detection of CPPE and empyema, the combination of pleural fluid CRP > or = 8.7 mg/dl and LDH > or = 1000 U/L was valuable in achieving a sensitivity, specificity, and AUC of 0.97/1,00/0.95. This study suggests that measurement of pleural CRP can be useful in the workup of patients with a parapneumonic effusion in order to differentiate CPPE from UPPE.

Constitutive expression of human angiostatin in Pichia pastoris by high-density cell culture

A high-density cell culture method to produce human angiostatin has been successfully established by constitutive expression of the protein in Pichia pastoris. The fermentation was carried out in a 20 l bioreactor with a 10 l working volume, using a high-density cell culture method by continuously feeding with 50% glycerol-0.8% PTM4 to the growing culture for 60 h at 30 degrees C. Dissolved oxygen level was maintained at 25-30% and pH was controlled at 5 by the addition of 7 M NH4OH. Angiostatin was constitutively expressed during the fermentation by linking its expression to the P. pastoris constitutive GAP promoter (pGAP). But after 36 h of fermentation, the peak biomass growth was 305 as measured by absorption of 600 nm, while the peak angiostatin expression was 176 mg/l. Similar to the product expressed from inducible system [24], angiostatin produced from constitutive system also inhibited the angiogenesis on the CAM and suppressed the growth of B16 melanoma in C57BL/6J mouse. The above results suggest that GAP promoter is more efficient than AOX1 promoter for the expression of angiostatin in P. pastoris by shake flask culture or high-density cell fermentation and is likely to be an alternative to AOX1 promoter in large-scale expression of angiostatin and other heterologous proteins.

Genetic association of blaSHV-5 with transposable elements IS26 and IS5 in Klebsiella pneumoniae from Taiwan

A cloned 5,248-bp EcoRI fragment from the Klebsiella pneumoniae transferable plasmid pKP53 (> 70 kb) containing bla(SHV-5) was sequenced. Insertion sequences IS26 and IS5 were found downstream from bla(SHV-5). The DNA sequences of the genetic environment surrounding bla(SHV-5) were homologous to plasmid p1658/97 from Escherichia coli, containing a truncated recF gene and a truncated deoR gene upstream and downstream from bla(SHV-5), respectively. RecF may be involved in bla(SHV-5) translocation to the plasmid by RecF-dependent recombination. This novel genetic environment may be associated with the successful proliferation and/or expression of SHV-5 in K. pneumoniae strains from Taiwan.

A Computational Study on the Kinetics and Mechanism for the Unimolecular Decomposition of o-Nitrotoluene

The kinetics and mechanism for the unimolecular decomposition of o-nitrotoluene (o-CH(3)C(6)H(4)NO(2)) have been studied computationally at the G2M(RCC, MP2)//B3LYP/6-311G(d, p) level of theory in conjunction with rate constant predictions with RRKM and TST calculations. The results of the calculations reveal 10 decomposition channels for o-nitrotoluene and its six isomeric intermediates, among them four channels give major products: CH(3)C(6)H(4) + NO(2), C(6)H(4)C(H)ON (anthranil) + H(2)O, CH(3)C(6)H(4)O (o-methyl phenoxy) + NO, and C(6)H(4)C(H(2))NO + OH. The predicted rate constants in the 500-2000 K temperature range indicate that anthranil production, taking place initially by intramolecular H-abstraction from the CH(3) group by NO(2) followed by five-membered ring formation and dehydration, dominates at temperatures below 1000 K, whereas NO(2) elimination becomes predominant above 1100 K and CH(3)C(6)H(4)O formation by the nitro-nitrite isomerization/decomposition process accounts for only 5-11% of the total product yield in the middle temperature range 800-1300 K. The branching ratio for CH(2)C(6)H(4)NO formation by the decomposition process of CH(2)C(6)H(4)N(O)OH is negligible. The predicted high-pressure-limit rate constants with the rate expression of 4.10 x 10(17) exp[-37000/T] s(-1) for the NO(2) elimination channel and 9.09 x 10(12) exp[-25800/T] s(-1) for the H(2)O elimination channel generally agree reasonably with available experimental data. The predicted high-pressure-limit rate constants for the NO and OH elimination channels are represented as 1.49 x 10(14) exp[-30000/T] and 1.31 x 10(15) exp[-38000/T] s(-1), respectively.

Detection of gentoxicity of benzidine and its derivatives with the Escherichia coli DJ 702 lacZ reversion mutagenicity assay

AIMS

The feasibility of Escherichia coli DJ 702 lacZ mutagenicity assay to detect genotoxicity of benzidine and its derivatives was evaluated.

METHODS AND RESULTS

DJ 702 strain was grown overnight at 30 degrees C in Luria-Bertani (LB) medium containing some components, such as chloramphenicol, ampicillin, delta-aminolevulinic acid, isopropyl-beta-d-thiogalactoside, and trace element mix. The mixtures of a bacterial culture and tested chemical at indicated doses were incubated at 30 degrees C for 30 min. Subsequently, 2 ml of molten top agar was added and the resulting mixtures were immediately poured onto a minimal lactose (ML) plate. Plates were incubated at 30 degrees C for 48 h. The number of colonies was determined by visual scoring. In this study, results showed that all the tested chemicals were mutagenic to DJ 702 strain.

CONCLUSIONS

E. coli lac mutagenicity assay using DJ 702 strain can detect the mutagenicity of benzidine and its derivatives.

SIGNIFICANCE AND IMPACT OF THE STUDY

We detected the mutagenicity of benzidine and its derivatives in E. coli lac mutagenicity assay using DJ 702, indicating that this assay may be used to detect benzidine and its derivatives in a powerful, sensitive, and convenient mutagenesis assay.

Enzymatic degradation of nitriles by Klebsiella oxytoca

Klebsiella oxytoca, isolated from cyanide-containing wastewater, was able to utilize many nitriles as sole source of nitrogen. The major objective of this study was to explore the ability of K. oxytoca to utilize some nitriles and then further evaluate the pathways of transformation of cyanide compounds by K. oxytoca. Results from this study indicate that succinonitrile and valeronitrile were the most optimal sources of nitrogen for the growth of K. oxytoca. The biodegradation of acetonitrile proceeded with the formation of acetamide followed by acetic acid. The production of ammonia was also detected in this biodegradation experiment. Similar results were observed in the propionitrile biodegradation experiments. Collectively, this study suggests that the breakdown of acetonitrile or propionitrile by this bacterium was via a two-step enzymatic hydrolysis with amides as the intermediates and organic acids plus with ammonia as the end products.

Psychophysics of prosthetic vision: I. Visual scanning and visual acuity

Recipients of vision prosthesis prototypes have reported electrically elicited visual perceptions as discrete dots of light (phosphenes). Phosphenes construct the scenery in discontinuous small isolated patches, resulting in visual information deficit to a large portion of the visual field. Visual scanning therefore plays an important role in the utility of prosthetic vision. In a psychophysical study, normally sighted subjects undertook a visual acuity task in a simulation of prosthetic vision with scanning facilitated by head movements. Subjects who adopted the circular scanning technique (4/12) correctly identified >60% of the test items, compared to subjects with no particular scanning patterns (3/12) with <50%. Increased head movement velocity was correlated to increased performance; at optimal scanning velocities, we estimated a 50% increase in identification rate or a two-fold improvement in visual acuity threshold compared to otherwise complete lack of scanning movement. Improved performance likely resulted from positive interactions with the temporal processes of the human visual system, which may as much as double the spatial information of that originally afforded by the phosphene lattice.

Detection of antibodies to phospholipase B in patients infected with Cryptococcus neoformans by enzyme-linked immunosorbent assay (ELISA)

Secreted phospholipases are virulence factors of several fungi, including Cryptococcus neoformans. We describe for the first time the detection by ELISA of antibodies to cryptococcal phospholipase B in the serum of patients infected with C. neoformans or C. gattii. Sixty-nine sera from 25 patients with cryptococcosis, 23 patients with Candida infections and 26 with bacterial or viral infections were tested. The sensitivity of the ELISA in patients with cryptococcosis was 100% in immunocompetent hosts and 64.3% in immunosuppressed patients with cryptococcal meningitis. Absorbance readings were significantly higher in immunocompetent patients (P<0.001). Titres remained positive for up to 2 years. Positive results were noted in 10 episodes of invasive candidiasis, three patients colonised with Candida, and three cases of bacterial infection. Mean absorbance readings were significantly lower in patients with bacterial infection (P <0.001). We conclude that phospholipase B is produced in vivo during cryptococcal infection and that serum phospholipase B antibodies are a sensitive marker of present or past infection. Cross-reactivity of the ELISA with sera from patients with candidiasis indicates that common epitopes are present on cryptococcal and candidal phospholipase B, hence fungal phospholipase B may constitute a new therapeutic target.

Factors affecting the biodegradation of PCP by Pseudomonas mendocina NSYSU

A pentachlorophenol (PCP) degrading bacterium was isolated from PCP-contaminated soils and identified as Pseudomonas mendocina NSYSU (P. mendocina NSYSU). The main objectives of this study were to (1) clarify the factors affecting the ability and efficiency of PCP biodegradation by P. mendocina NSYSU, and (2) optimize the use of this bacterium in bioremediation of PCP. Microcosm experiments were conducted to fulfill the objectives. In batch cultures, P. mendocina NSYSU used PCP as its sole source of carbon and energy and was capable of completely degrading this compound. This was confirmed by the stoichiometric release of chloride ion. Moreover, P. mendocina NSYSU was able to mineralize a high concentration of PCP (150 mg/L). Results from the oxygen concentration experiment reveal that the growth of P. mendocina NSYSU was inhibited under low oxygen and anaerobic conditions. Results indicate that the optimal growth conditions for P. mendocina NSYSU include the following: slightly acidic (6<pH<7), aerobic, and relatively moderate ambient temperature (20 degrees C<temperature<30 degrees C) conditions. Addition of extra carbon sources (sodium acetate and glucose) could not enhance the PCP biodegradation. No PCP byproducts were detected after eight days of incubation in this study. This suggests that P. mendocina NSYSU is able to effectively biodegrade PCP and its biodegradation byproducts without the accumulation of inhibitory toxic compounds. Results from this study could be used to assist the optimization of its use in bioremediation of PCP.

Numerical simulation of surface-plasmon-assisted nanolithography

In this paper, based on numerical study using Finite Difference Time Domain method, we discuss two possible illumination schemes utilizing surface plasmon effects to achieve high density sub-100 nm scale photolithography by using ultraviolet light from a mercury lamp. In the illumination schemes discussed in this paper, a thin film layer, named as shield layer, is placed in between a photoresist layer and a silicon substrate. In the first scheme, the shield material is titanium. Simulations show that the surface plasmons excited on both the metallic mask and the titanium shield enable the transfer of high density nanoscale pattern using mercury lamp emission. In the second scheme, a silicon dioxide layer is used instead of the titanium to avoid possible metal contamination. The two schemes discussed in this paper offer convenient, low cost, and massive pattern transfer methods by simple adjustment to the traditional photolithography method.

Utilization of the metal-cyano complex tetracyanonickelate (II) by Azotobacter vinelandii

AIMS

The ability of Azotobacter vinelandii, a N(2)-fixing bacterium, to biodegrade tetracyanonickelate (TCN) was evaluated.

METHODS AND RESULTS

The amounts of TCN were measured spectrophotometrically. Ammonia was determined colorimetrically by the indophenol method. The produced methane from TCN conversion by A. vinelandii was detected by gas chromatography. Results showed that A. vinelandii was able to biodegrade 1 mmol l(-1) of TCN. Ammonia and methane were detected during the process of TCN degradation. Effects of exogenous nitrogen sources on TCN degradation were addressed in this study. Results revealed that the addition of ammonia (1, 5 and 10 mmol l(-1)) into the reaction mixtures caused decrease of TCN degradation rate during a 24-h incubation period. This inhibition was also observed when nitrite (5 and 10 mmol l(-1)) was added, whereas TCN degradation still proceeded after the addition of nitrate at the same concentrations. Furthermore, the rate of TCN utilization was strikingly enhanced when 0.8% of glucose was added.

CONCLUSIONS

Azotobacter vinelandii can degrade 1 mmol l(-1) of TCN into ammonia and methane. However, the inhibitory effects of exogenous ammonia and nitrite on TCN degradation by this bacterium were found in this study.

SIGNIFICANCE AND IMPACT OF THE STUDY

This is the first report defining the capability of A. vinelandii to degrade TCN. This bacterium might have potential value in applied strategies for removing metal-cyano wastes. Furthermore, these findings would be helpful in designing a practical system inoculated with A. vinelandii for the treatment of TCN.

Inhibition of nitric oxide can ameliorate apoptosis and modulate matrix protein gene expression in bacteria infected chondrocytes in vitro

Bacterial infection stimulates nitric oxide (NO) production in chondrocytes. However, the role of NO in chondrocyte apoptosis after infection remains unclear. The purpose of the study was to test if inhibition of NO could ameliorate apoptosis and modulate matrix protein gene expression in bacteria-infected chondrocytes. It was shown that pre-treating chondrocytes with L-NAME (1 mM) significantly decreased the release of NO (from 72 to 14 microM) and the extent of apoptosis (from 52.9% to 18.9%). Pre-treatment with L-NAME also counteracted the bacteria-induced downregulation of Type II collagen (from 26% to 79%) and aggrecan (from 63% to 105%) mRNA levels. Inhibition of NO after the induction of infection could not decrease the extent of apoptosis and modulate matrix protein gene expression. The results of this study support the hypothesis that NO has an important role in bacteria-induced chondrocyte apoptosis. Pre-treatment but not post-treatment could ameliorate the extent of apoptosis and reestablish the cartilage matrix protein gene expression. This study suggests that in addition to NO, other mechanisms may be responsible for the sustained destruction of articular cartilage in the post-infectious arthropathy.

Visual acuity measurement of prosthetic vision: a virtual-reality simulation study

A virtual-reality simulation tested prosthetic visual acuity for both rectangular and hexagonal phosphene grids. Thirteen normally sighted, untrained subjects were required to identify the Landolt C optotype over ten sessions. Overall performance, performance by filter setting (image analysis), and performance by size and orientation of the Landolt C optotype are reported. The results indicated that the hexagonal grid had a slight (4.1%) but statistically significant (p < 0.0001) performance advantage over the rectangular grid for correct identification of the testing symbol. It was also observed that both the phosphene grids had distinct performance profiles relating to their respective spatial orientation. Over the course of the ten sessions, learning afforded subjects an averaged improved performance of 10%.